package com.bluefox.utils;

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

/**
 * @CLassName SpringContextHolder
 * @Description TODO
 * @Author 孙峰
 * @Date 2020/1/1 14:43
 * @Version 1.0
 */
@Slf4j
public class SpringContextHolder implements ApplicationContextAware, DisposableBean {
    private static ApplicationContext applicationContext = null;


    public static ApplicationContext getApplicationContext() {
        return applicationContext;
    }

    /**
     * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
     */
    @SuppressWarnings("unchecked")
    public static <T> T getBean(String name) {
        assertContextInjected();
        return (T) getApplicationContext().getBean(name);
    }
    /**
     * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
     */
    public static <T> T getBean(Class<T> requiredType) {
        assertContextInjected();
        return getApplicationContext().getBean(requiredType);
    }

    /**
     * 检查ApplicationContext不为空.
     */
    private static void assertContextInjected() {
        if (getApplicationContext() == null) {
            throw new IllegalStateException("applicationContext属性未注入, 请在applicationContext" +
                    ".xml中定义SpringContextHolder或在SpringBoot启动类中注册SpringContextHolder.");
        }
    }
    /**
     * 清除SpringContextHolder中的ApplicationContext为Null.
     */
    private static void clearHolder() {
        log.debug("清除SpringContextHolder中的ApplicationContext:"
                + getApplicationContext());
        applicationContext = null;
    }
    @Override
    public void destroy() throws Exception {
        SpringContextHolder.clearHolder();
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        if (SpringContextHolder.getApplicationContext() != null) {
            log.warn("SpringContextHolder中的ApplicationContext被覆盖, 原有ApplicationContext为:" + SpringContextHolder.applicationContext);
        }
        SpringContextHolder.applicationContext = applicationContext;
    }
}
